A bent pipe may be subjected to a relatively large external force during manufacture, transportation and installation, resulting in deformation of the bent portions of the pipe, thereby changing the bending angle of the entire pipe. However, this is very unfavourable and even totally unacceptable for applications where the bent pipe needs to meet high requirements. For example, in a semiconductor refrigerator, a heat exchanging device composed of a refrigerant case and a bent pipe is often used to transfer heat from the hot end of a semiconductor cooler to the housing or to transfer cold from the cold end of the semiconductor cooler to a storage compartment of a liner. As the refrigerant case and the bent pipe are filled with a refrigerant and the refrigerant is allowed to flow therein and undergo phase-change heat exchange, so that the cold from the cold end of the semiconductor cooler is transferred to the liner of the refrigerator, or the heat from hot end of the semiconductor cooler is transferred to the housing of the refrigerator, it has to be ensured that the refrigerant flows in the bent pipe and is effectively evaporated or condensed, which imposes high requirements for the bent pipe.